The Research Of Microstructure And Mechanical Properties On Zr-based Bulk Metallic Glass

In this dissertation, tapered sample of Zr base BMG and legal system by suspend melting under an argon atmosphere using a water-cooled Cu mold.The research on bulk amorphous alloys and amorphous composites about glass-forming ability,plastic,microstructure,mechanical properties,the mechanism of produce large plastic fracture and shear zone theory. The three main aspects involved in the work:The first and follow is comprehensive research on microstructure and glass-forming ability。The second part research on the plastic, mechanical properties for (Zr_0.72Cu_0.165Ni_0.115)9_90+x Al_10-x (x=-1,-2,-3,-4,0,2,4,6).Finding the plastic properties and intensity of amorphous alloy excellent ingredients as(Zr_0.72Cu_0.165Ni_0.115)₈₈Al₁₂ (d=3mm,4mm,6mm),The plastic strain to 20.56%,total strain to 27.78%,breaking strength biggest reached 2030.7 MPa,hardness of 579.5HV for the sample of this ingredients that can think of amorphous alloy superplastic with room temperature.Based on the plastic and strength so excellent of this alloy,the last part mainly research on the excellent ingredients of (Zr_0.72Cu_0.165Ni_0.115)₈₈Al₁₂ (d=3mm,4mm,6mm) alloy in different sizes of glass-forming ability,mechanical properties,fracture mechanism and shear zone model theory etc,and found that the ingredients sample under different size, as the Diameter increase, glass-forming ability and the plastic of alloy is decreased,TEM phase photographs and diffraction pattern results is also provided a conclusion. While the plastic deformation of 4mm samples is to 2.6% and the plastic deformation of 6mm sample is to 0.2%. The compression fracture of amorphous in appeared typical, dense rivers shape pattern,the fracture Angle of Compression is different and shear zone density and sizes is also different,that basicly are 45o below. The number of shear zone is reduce and the size is bigger with the sample size increased.The strength and hardness of this alloy with the size increased are also decreased, for example, the intensity of 4mm sample is 1552.7MPa,the hardness of 4mm is 676.6HV and the intensity of 6mm sample is 1330.8MPa,the hardness of 6mm is 554.8HV,Comprehensive above, glass-forming ability,plastic, the mechanical properties ,the number and volume of shear band for(Zr_0.72Cu_0.165Ni_0.115)₈₈Al₁₂ (d=3mm,4mm,6mm) alloy all show a certain size differences. Meaning that the alloy of various performance by the size of the effect of comparison is obvious.